Commerical processes for producing BCl.sub.3 (boron trichloride) result also in the production of the impurity COCl.sub.2 (phosgene). The removal of COCl.sub.2 has been a problem, particularly where it is desired not to introduce other contaminants in the BCl.sub.3 either by the process directly or indirectly. COCl.sub.2 causes difficulties when BCl.sub.3 is used in the electronics industry in the manufactured of electrical components, when BCl.sub.3 is used as a catalyst in numerous ways such as in the production of styrene, when BCl.sub.3 is used as an additive for high energy fuels, or when BCl.sub.3 is used in the refining of various refractory metals, etc. In the past, removal of the impurity from BCl.sub.3 by economical methods has proven unsuccessful.
More recently, U.S. Pat. No. 4,063,896 issued to James A. Merritt and Lawrence C. Robertson on Dec. 20, 1977 and assigned to The United States of America as represented by the Secretary of the Army, discloses a method wherein phosgene as an impurity in BCl.sub.3 is dissociated by CO.sub.2 laser radiation. In this method the power level of a cw CO.sub.2 multiline laser can be varied to accomplish the irradiation to effectively dissociate the COCl.sub.2 into its dissociation products, substantially CO and Cl.sub.2. The BCl.sub.3,.nu..sub.3 (956 cm.sup.-1) fundamental is resonant with CO.sub.2 (P.sub.20) laser line and strongly absorbs this energy which is followed by an intramolecular V-V transfer of energy to the COCl.sub.2 which results in its dissociation. The gaseous compound C.sub.2 H.sub.4 having combination bands and overtones that match reasonably close to the energy levels of COCl.sub.2 can also serve as a diluent for COCl.sub.2 to effect transfer of energy for dissociation of COCl.sub.2 by cw CO.sub.2 laser radiation.
Although the aforementioned method for removing COCl.sub.2 from BCl.sub.3 by laser is a meritorious achievement, the method has the limitation of requiring a laser source.
Therefore, an object of this invention is to provide a method which does not require a laser for purifying BCl.sub.3 of the impurity COCl.sub.2.
Another object of this invention is to provide a method for purifying BCl.sub.3 of the impurity COCl.sub.2 by an electric excitation selected from electrical discharge excitations, radio frequency excitation, or electron beam excitation.